关键词: 四川盆地, 海相高演化层系, 伊利石结晶度, 沥青反射率, 成熟度指标, 成岩演化

Abstract:

In combination with the geological background and sedimentary evolution in the eastern Sichuan Basin,the data of illite crystallinity,vitrinite reflectance(VR_o),bitumen reflectance(BR_o)and homogenization temperature of fluid inclusions of Mesozoic-Paleozoic core (debris) samples show that Mesozoic continental strata in eastern Sichuan Basin are characterized with illite crystallinity values over 0.42°(Δ2θ),the VR_o and BR_o less than 3%,and lies in late diagenetic stage.Mesozoic-Paleozoic marine strata are characterized with illite crystallinity values from 0.25 to 0.42°(Δ2θ),the VR_o and BR_o from 3% to 6.5%,and lies in very low-grade metamorphic stage.The value of illite crystallinity has a good linear relation with homogenization temperature of fluid inclusions and the paleotemperature deduced from VR_o.While the value of illite crystallinity is equal to 0.42°(Δ2θ),the paleotemperature and homogenization temperature of inclusions are about 180℃.The illite crystallinity value is an indicator of important thermal maturity and paleotemperature at the digenetic-metamorphic and high-over mature stages.

Key words: Sichuan Basin, high-maturity marine strata, illite crystallinity, bitumen reflectance, maturity indicator, diagenetic evolution